Gemini 2.5 Flash vs GPT-5.5 Pro
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Gemini 2.5 Flash and GPT-5.5 Pro.
Gemini 2.5 Flash
Gemini 2.5 Flash is Google's state-of-the-art workhorse model, specifically designed for advanced reasoning, coding, mathematics, and scientific tasks. It includes built-in "thinking" capabilities, enabling it to provide responses with greater...
GPT-5.5 Pro
GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...
Technical Specifications
| Specification | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| Provider | OpenAI | |
| Context Window | 1,048,576 tokens | 1,050,000 tokens |
| Agent Suitability | N/A | 98/100 |
| Time to First Token (TTFT) | N/A | 450 ms |
| Deployment Model | managed api | managed api |
| Production Stability | beta | beta |
| API Available | Yes | Yes |
| Released Date | 2025-06-17 | 2026-04-24 |
API Pricing Comparison
Input Price per Million Tokens
Gemini 2.5 Flash
$0.30
GPT-5.5 Pro
$30.00
Output Price per Million Tokens
Gemini 2.5 Flash
$2.50
GPT-5.5 Pro
$180.00
Want to test both models live?
Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.
Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Gemini 2.5 Flash Quirks & Gotchas
No developer gotchas reported.
GPT-5.5 Pro Quirks & Gotchas
- ▸Best-in-class instruction following for complex agentic chains
- ▸Premium pricing — use GPT-5 for cost-sensitive workloads